Production of phenols



United States Patent PRODUCTION OF PHENOLS Geert J. De Jong, Geleen, Netherlands, assignor to Stamicarbon N.V., Heerlen, Netherlands No Drawing. Application August 4, 1953 Serial No. 372,377

Claims priority, application Netherlands August 16, 1952 6 Claims. (Cl. 260-621) The present invention relates to phenols and its principal object is to provide novel procedures for preparing phenols involving decomposition of the hydroperoxides of aromatic hydrocarbons containing a secondary or tertiary aliphatic group. Such procedures also yield ketones or aldehydes in addition to the phenols.

Another object of the invention is to provide procedures for obtaining phenols in high yields from the above mentioned hydroperoxides.

A further object of the invention is the provision of new procedures for making phenols which are uniquely adapted for continuous operation.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood however, that the detailed description and specific example, while indicating preferred embodiments of this invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

The foregoing objects are accomplished, according to the present invention, by a process involving the steps of: acidifying the selected hydroperoxide-in a current of steam, thereby decomposing the hydroperoxide and forming a phenol and other products of decomposition, namely, ketone or aldehyde, which are entrained in the steam, along with some unreacted starting material, condensing the steam containing said phenol and thereafter recovering the phenol from the condensate.

It has previously been known that hydroperoxides can be decomposed by heating in an acid medium. Thus, for example, it is known to be possible to convert isopropyl benzene hydroperoxide in this way into phenol and acetone. Di-isopropyl benzene peroxide can also be decomposed in the same manner.

Furthermore, it is also known that a phenol can be recovered from a reaction mixture containing the same by distilling the reaction mixture with steam and thereafter separating'the phenol from the steam distillate. Likewise, it is known that steam distillation may be used to separate phenols from the reaction products contained by the decomposition of hydroperoxides.

In contrast to these prior proposals, however, the hydroperoxide decomposition is effected in the presence of steam, according to the present invention, so that production of the phenols and removal thereof from the decomposition stage by the steam, along with ketones and aldehydes formed during decomposition, is carried out almost simultaneously. In this way, it has been discovered that the hydroperoxide starting material is prevented from oxidizing the reaction products and from being converted into by-products from which no phenols can be obtained. At the same time, removal of the phenols as they are formed according to the invention obviates the formation of undesirable oxidation products. Accordingly, the process of the invention permits substantially 2,883,430 Patented Apr. 21, 1959 higher yields of phenols to be obtained than has hitherto been possible.

The temperature at which decomposition is effected can be widely varied. Thus, for example, temperatures within the range of to 140 C. give satisfactory results, although preferably decomposition is carried out at a temperature of about 100 C. utilizing steam at atmospheric pressure. Steam at superatmospheric pressures giving temperatures of the order of to C. may also be used to advantage, the reaction proceeding somewhat faster the higher the temperature utilized. As will be appreciated, the amount of steam utilized necessarily will vary, depending upon such factors as steam pressure. However, generally speaking, sufiicient steam should be used to maintain the decomposition temperature and remove the desired decomposition products.

The use of steam in the procedures of the present. invention offers the further advantage of permitting the hydroperoxide to be heated in a simple and convenient manner which permits the preferred decomposition temperature of about 100 C. at atmospheric pressure to be easily maintained without the danger of overheating the hydroperoxide. Likewise, when steam is utilized at superatmospheric pressures, the temperature of the hydroperoxides may be easily maintained. at a dseirabl'e working temperature, e.g., 100 to 120 C., at which temperature the decomposition, as indicated above proceeds somewhat faster.

Decomposition of the hydroperoxide, according to the present invention, may be carried out by mixing together the hydroperoxide and a dilute acid with stirring and introducing steam into the resulting mixture. The steam vapor leaving the reaction vessel and containing the phenol and other reaction produtcs formed by decomposition is condensed and the desired phenol subsequent- 'ly recovered in conventional manner from the condensate.

As suitable acids for effecting decomposition, there may be mentioned sulfuric acid, phosphoric acid, hydrochloric acid and strong organic acids such as toluene sulfonic acids and while the concentration thereof may be widely varied, it is preferred to have the concentration fall within the range of 5% to 50% by weight. Preferably, from 1 to 5 parts by weight of acid are used per part of hydroperoxide, although proportions outside the range stated may also be used to advantage. For best results, from 3 to 4 parts of 10% to 25% sulfuric acid are used per part of hydroperoxide, on a weight basis.

The hydroperoxide of any aromatic hydrocarbon containing a secondary or tertiary aliphatic group may be decomposed, according to the process of the invention. Accordingly, as suitable hydroperoxides there may be mentioned the hydroproxides of isopropylbenzene; di-isopropylbenzene, isopropyl naphtalene, phenylcyclohexane; diparatolylmethane; 1,1 diphenyl ethane; 1,1-diparatolylethane; and diphenylmethane. Suitable procedures for making the hydroperoxides of diparatolylmethane and 1,1- diparatolylethane, involving oxidation of the hydrocarbon with oxygen, are described and claimed in my copending application, Serial No. 355,670, filed May 18, 1953, and now abandoned, the subject matter of which is made a part of this application by reference.

The procedures of the invention may be carried out in batch form or continuously. Continuous operations are preferred and may be effected by continuously introducing the steam and hydroperoxide into a reaction vessel containing the dilute acid, and continuously withdrawing therefrom the vapors containing entrained phenol and by-product ketone or aldehyde. A continuous process, such as that described, olfers the advantage that only a small amount of hydroperoxide need be present in the reaction vessel, thus eliminating the necessity of heating large amounts of hydroperoxide at the same time. This makes the operations of the invention substantially safer and permits the use of a minimum amount of apparatus. For use in the present invention, the hydroperoxides need not be in the pure state, i.e., they may be used in the form of the reaction product obtained in the process of Serial No. 355,670 comprising a solution of the hydroperoxide in the hydrocarbon, i.e., diparatolylmethane or 1,1-diparatolylethai1e. This is one of the most important advantages of the present invention, since it means that there is no necessity for separating or otherwise purifying the hydroperoxide prior to its decomposition.

When the hydroperoxide is utilized in admixture with the hydrocarbon from which it is derived, the latter may be recovered from the reaction mixture after decomposition of the hydroperoxide has been completed. The last mentioned condition can be readily ascertained by checking the phenol content of the steam issuing from the reaction vessel and when it is found that the phenol content has taken a substantial drop, the reaction liquid may be removed from the reaction vessel and permitted to separate out into two layers, an oil layer and a water layer. The oil layer contains the non-converted hydrocarbon and after being washed with alkali metal hydroxide, e.g., sodium hydroxide, to remove any phenol dissolved therein as a phenolate, may be re-used in the preparation of the desired hydroperoxide.

The invention is further illustrated by the following example which is given for purposes of illustration only and wherein parts and percentages referred to are by weight.

' Example A reaction liquid obtained in the preparation of diphenyl methane hydroperoxide by oxidation of diphenyl methane with oxygen, and which, in addition to nonoxidized diphenyl methane, contains 16% by Weight of hydroperoxide, was continuously introduced with stirring into a reaction vessel in which 1500 parts of sulfuric acid were heated to a temperature of 100 C. by the introduction of steam into the vessel. The vapor issuing from the reaction vessel was condensed and the condensate separated into an oily layer and a water layer.

From the oily layer which, in addition to phenol, also contained benzaldehyde, the phenol was recovered by extraction with an aqueous sodium hydroxide solution leaving the benzaldehyde for separate treatment. The resultant aqueous phenolate solution was neutralized with sulfuric acid and added to the water layer separated from thecondensate. By extraction with benzene, the phenol was subsequently separated from this aqueous layer and recovered by distillation.

The liquid contained in the reaction vessel was con tinuously removed therefrom and separated into two lay ers, one of which, namely, the aqueous layer containing sulfuric acid, was continuously returned to the reaction vessel. The sulfuric acid concentration was maintained at 10 to 20%. The only layer, which consisted mainly of unconverted diphenyl methane but still contained about 1% of hydroperoxide and some phenol, was washed with a dilute aqueous sodium hydroxide solution to remove the phenol present (the resulting phenolate solution was added to the phenolate solution obtained from the aforementioned condensate). The washed oil was subsequently reconditioned by neutralization with carbon dioxide for further use as a starting material for the oxidation with oxygen to obtain the hydroperoxide.

When operating continuously in the manner outlined above, using 1500 parts of the starting solution every hour, parts of phenol and parts of benzaldehyde were obtained.

In the benzaldehyde distillation still unconverted diphenyl methane was left as a residue which was re-used to obtain the hydroperoxide in the manner set forth above.

It will be appreciated that since both the peroxides and hydroperoxides of aromatic hydrocarbons which possess a secondary or tertiary aliphatic group are decomposed in acid medium into phenols and ketones or aldehydes, the term hydroperoxides as used herein is considered for purposes of simplicity to encompass the corresponding peroxides. Likewise, the term phenols is intended to encompass not only phenol itself, but other corresponding mono and polyhydroxy compounds of higher molecular weight, e.g., cresols, Xylenols and the like.

It will also be appreciated that various modifications of the invention as described herein can be made without in any way deviating from the scope thereof as set forth in the following claims.

I claim:

1. A process for producing a phenol from a hydroperoxide of an aromatic hydrocarbon selected from the group consisting of aromatic hydrocarbons containing secondary and tertiary aliphatic groups, said process including the steps of acidifying said hydroperoxide in a current of steam thereby decomposing said hydroperoxide and forming phenol entrained in said steam, condensing the steam containing phenol and recovering the phenol from said condensate.

2. The process of claim 1, wherein said steps are carried out continuously.

3. The process of claim 1, wherein said acidification is carried out at a temperature of about 100 C. maintained by said steam.

4. The process of claim 1, wherein the hydroperoxide decomposed is in admixture with the hydrocarbon from which it is derived.

5. The process of claim 1, wherein 10 to 25% sulfuric acid is used in said acidifying step.

6. The process of claim 1, wherein the acidifying step is effected by passing the steam and hydroperoxide into acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,110,829 Dreisbach Mar. 8, 1938 2,359,212 Frank et al Sept. 26, 1944 2,367,623 Schulze et al. June 16, 1945 2,407,045 Tyrer Sept. 3, 1946 2,628,983 Aller et al. Feb. 17, 1953 2,661,375 Conner Dec. 1. 1953 

1. A PROCESS FOR PRODUCTING A PHENOL FROM A HYDROPEROXIDE OF AN AROMATIC HYDROCARBON SELECT FROM THE GROUP CONSISTING OF AROMATIC HYDROCARBONS CONTAINING SECONDARY AND TERTIARY ALIPHATIC GROUPS, SAID PROCESS INCLUDING THE STEPS OF ACIDIFYING SAID HYDROPEROXIDE IN A CURRENT OF STEAM THEREBY DECOMPOSING SAID HYDROPEROXIDE AND FORMING PHENOL ENTRAINED IN SAID STEAM, CONDENSING THE STEAM CONTAINING PHENOL AND RECOVERING THE PHENOL FROM SAID CONDENSATE. 